This invention relates to methods and devices for modifying microwave energy fields, having utility in the microwave heating of bodies of material exemplified by (but not limited to) foodstuffs.
It is well known that the conventional microwave cooking or heating of a food load does not provide effective browning or crispening of the food surfaces. Those food products that have a surface composed of a material different from that of the main portion of the food article, such as a crust or a layer of batter or breading, for example a pie or a breaded fish fillet, require this separate surface layer to reach a higher temperature than the bulk of the food, in order that such surface layer be browned or crispened. For this reason, a conventional convection oven set at a relatively high temperature has been the traditional method of cooking such food products.
There are also other types of food articles in which the nature of the surface layer is essentially the same as that of the main portion of the article, but it nevertheless requires to be browned and/or crispened. Examples in this category are the undersurface of a pizza, the two surfaces of a pancake, hash brown potatoes or french fried potatoes.